Different methods of monitoring the operation of a display panel are known in the state of the art, with the aim of e.g. detecting correct or incorrect operation of the display panel.
In most of the cases, reference performance values need to be stored in advance (i.e., at the factory, during calibration) in order to determine the condition/status of the display panel. In other cases, intervention of the user is counted to detect malfunction of the display panel. In further cases, reference values are continuously updated, wherein determination of those values is an obtrusive operation (e.g. displaying patterns across the screen) and cannot be performed in parallel with normal use of the display screen.
US2016/0217719 A1 discloses a test method for a screen (such as e.g. an OLED screen) in a vehicle comprising the steps of: displaying a raster image on a screen, measuring the electrical current intensity flowing as a result; and comparing the measured electrical current intensity to a stored reference current intensity. It is ascertained whether the raster image was generated without errors dependent on the comparison. The reference current intensity has been determined at manufacture or production time. Accuracy of this method may deteriorate over time due to the aging of the screen, since intensity measurements obtained at different times in the operation life of the screen may significantly differ from each other.
WO2008120143 A2 discloses a method for determining a status and/or condition of an LED/OLED device, comprising the steps of: applying at least one time varying signal to the LED/OLED device, acquiring the response to the at least one time varying signal, correlating the response with predetermined values, and determining the status/condition on the basis of the correlation result. The time varying signals may be selected out of the group of: sinusoidal signals, chirp signals, wideband signals, small band signals, single frequency signals, multi frequency signals, step signal or ramp signals. The user of the LED/OLED unit will not recognize the operation of the diagnostic device since the applied time varying signals are very small and hence do not result in an illumination of the LED/OLED unit. The time varying signals are added or superimposed to the power voltage supplied to the OLED.
DE102014220373 describes the difficulty of implementing displays in automotive applications for displaying critical information (warning lights, etc.) while staying within the limits set by the ASIL requirements. A screen is used for displaying critical information in an area of the screen that the user checks frequently, so that the user himself becomes aware of a malfunction of the display. This method thus looks for an increase in safety of a display panel used in automotive applications but counts on the user to detect malfunction of the panel.
US2007013693 A1 relates to critical applications of displays in the field of avionics. An integrity check method for an aircraft cockpit display is discussed in the prior art document, wherein aircraft sensor information is sent to a graphics rendering processor for rendering an image to be presented in a cockpit display. In parallel, a second processor calculates a number of points of a subset of the image (“points of light”), which are then compared to the full-rendered image. The integrity check passes if the subset of points (“points of light”) coincides with the full-rendered image. This prior art method is therefore focused on avoiding corruption of sensitive data being sent to the panel, rather than on determining adequate or defective functioning of the display panel irrespective of the data sent to the panel.
US20110227964A1 discloses a system and method for deriving a sequence of OLED non-uniformity test patterns. A pattern generator generates a full sequence of display patterns according to a transform function, such as a discrete cosine transformation or wavelet transformation. A driver drives a display with each of the sequence of patterns. A sensor senses a property of the display, such as a total current for the display, for each of the sequence of patterns. An extraction unit derives a pixel non-uniformity model using the sensed properties and an inverse of the transform function. Patterns that contribute less than a threshold amount to the non-uniformity model can be identified and deleted to derive a sparse sequence of patterns, which can be stored in a memory. The sparse sequence of patterns can be used to test the display and extract a set of pixel non-uniformity values. The pixel non-uniformity values can be used to generate a correction signal for the display. In the proposed system and method, reference values are thus continuously established (and updated) by performing an obtrusive operation (displaying patterns across the screen) which cannot be performed in parallel with normal use of the display screen.
An object of the present disclosure is improving the prior art methods, computer programs and controllers (systems) for detecting correct or incorrect operation of a display panel.